chapter 14 - reconstructing and using phylogenies

Question 1

define phylogeny

Answer 1

the evolutionary history of relationships among organisms or their genes

Question 2

how are phylogenies demonstrated?

Answer 2

phylogenetic tree diagrams

Question 3

each node (split) of the tree represents:

Answer 3

a divergence of lineages

Question 4

T or F: rotation at the nodes and therefore the vertical order of the lineages are arbitrary

Answer 4

true

Question 5

define the tree of life

Answer 5

the unifying concept of biology - all life is connected through evolutionary history

Question 6

define convergent evolution:

Answer 6

independently evolved traits subject to similar selection pressures and may become superficially similar
two separate species may develop the same traits even though their common ancestor did not have it

Question 7

define homoplasies (homoplastic traits)

Answer 7

similar traits that are generated by convergent evolution and evolutionary reversals

Question 8

define evolutionary reversal

Answer 8

when a trait returns from a more advanced character to a more primitive one

Question 9

define homologs

Answer 9

features shared by 2+ species that were inherited from a common ancestor

Question 10

define homologs

Answer 10

features shared by 2+ species that were inherited from a common ancestor

Question 11

define ancestral vs derived characteristics

Answer 11

ancestral: characteristic of a homologous trait that was present in the ancestor of the group
derived: a trait found in a descendent that was not present in the ancestor

Question 12

define synamorphies

Answer 12

derived characteristics shared among a group that are viewed as evidence of common ancestry of the group

Question 13

define ingroup vs outgroup when constructing phylogenetic trees

Answer 13

ingroup: the group of primary interest
outgroup: closely related species/group known to be phylogenetically outside the group of interest

Question 14

what is the parsimony principle?

Answer 14

the theory that the simplest explanation of observed data for a phylogeny is the preferred explanation
minimizes the # of evolutionary changes that must be assumed (fewest homoplasies)

Question 15

define Occam’s razor

Answer 15

the best explanation fits the data with the fewest assumptions

Question 16

what kind of traits are used to construct phylogenies? (5)

Answer 16

morphological, fossil, developmental, molecular, behavioral, etc.

Question 17

define a taxon

Answer 17

any group of organisms that is treated as a unit

ex. a genus, or all insects

Question 18

what is the pattern of taxonomic classification?

Answer 18

domain –> kingdom –> phyla –> classes –> orders –> families –> genera –> species

Question 19

define a monophyletic taxon

Answer 19

1 taxon contains an ancestor and all descendants of that ancestor, and no other organisms
the clade can be removed from the tree with a single “cut”

Question 20

define a clade

Answer 20

a group of organisms believed to have evolved from a common ancestor
a taxon is a clade

Question 21

define paraphyletic taxonomy

Answer 21

a group that does not include all descendants of a common ancestor

Question 22

define a polyphyletic taxon

Answer 22

a group that does not include its common ancestor

Question 23

what is the molecular clock hypothesis?

Answer 23

rates of molecular change are constant enough to predict the timing of evolutionary divergence

Question 24

how to calibrate a molecular clock?

Answer 24

uses the average rate at which a given gene/protein accumulates changes to gauge the timing of divergences